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SubjectRe: [PATCH] x86/pci: Add a break condition when enabling BAR
Date
Christian König <christian.koenig@amd.com> writes:

> Hi Bandas,
>
> thanks for the patch, but this is a known issue with a fix already on
> the way into the next -rc.

Oh great! Thank you, have a pointer to the patch so that I can test ?

> Regards,
> Christian.
>
> Am 07.12.2017 um 09:00 schrieb Bandan Das:
>> On an old flaky system with AMD Opteron 6320, boot hangs
>> with the following trace since commit fa564ad9:
>>
>> [ 28.181012] Hardware name: HP ProLiant DL385p Gen8, BIOS A28 09/03/2014
>> [ 28.184022] RIP: 0010:lock_acquire+0xd5/0x1e0
>> [ 28.185010] RSP: 0018:ffffb7ad818c39a8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff11
>> [ 28.187010] RAX: ffffa074fb39b140 RBX: 0000000000000246 RCX: 0000000000000000
>> [ 28.189014] RDX: ffffffffb20a55a9 RSI: 0000000000040009 RDI: 0000000000000246
>> [ 28.191012] RBP: 0000000000000000 R08: 0000000000000006 R09: 0000000000000000
>> [ 28.193020] R10: 0000000000000001 R11: 00000000dac664b5 R12: 0000000000000000
>> [ 28.196013] R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000
>> [ 28.197011] FS: 0000000000000000(0000) GS:ffffa074fbd00000(0000) knlGS:0000000000000000
>> [ 28.201014] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [ 28.201014] CR2: 0000000000000000 CR3: 00000003b6e10000 CR4: 00000000000406e0
>> [ 28.205008] Call Trace:
>> [ 28.205013] ? request_resource_conflict+0x19/0x40
>> [ 28.207013] _raw_write_lock+0x2e/0x40
>> [ 28.209008] ? request_resource_conflict+0x19/0x40
>> [ 28.209010] request_resource_conflict+0x19/0x40
>> [ 28.212013] pci_amd_enable_64bit_bar+0x103/0x1a0
>> [ 28.213025] pci_fixup_device+0xd4/0x210
>> [ 28.213025] pci_setup_device+0x193/0x570
>> [ 28.215010] ? get_device+0x13/0x20
>> [ 28.217008] pci_scan_single_device+0x98/0xd0
>> [ 28.217011] pci_scan_slot+0x90/0x130
>> [ 28.219010] pci_scanild_bus_extend+0x3a/0x270
>> [ 28.321008] acpi_pci_root_create+0x1a9/0x210
>> [ 28.321014] ? pci_acpi_scan_root+0x135/0x1b0
>> [ 28.324013] pci_acpi_scan_root+0x15f/0x1b0
>> [ 28.325008] acpi_pci_root_add+0x283/0x560
>> [ 28.325014] ? acpi_match_device_ids+0xc/0x20
>> [ 28.327013] acpi_bus_attach+0xf9/0x1c0
>> [ 28.329008] acpi_bus_attach+0x82/0x1c0
>> [ 28.329044] acpi_bus_attach+0x82/0x1c0
>> [ 28.331010] acpi_bus_scan+0x47/0xa0
>> [ 28.333008] acpi_scan_init+0x12d/0x28d
>> [ 28.333013] ? bus_register+0x208/0x280
>> [ 28.333013] acpi_init+0x30f/0x36f
>> [ 28.335010] ? acpi_sleep_proc_init+0x24/0x24
>> [ 28.337013] do_one_initcall+0x4d/0x19c
>> [ 28.337013] ? do_early_param+0x29/0x86
>> [ 28.340013] kernel_init_freeable+0x209/0x2a4
>> [ 28.341008] ? set_debug_rodata+0x11/0x11
>> [ 28.341011] ? rest_init+0xc0/0xc0
>> [ 28.343013] kernel_init+0xa/0x104
>> [ 28.345008] ret_from_fork+0x24/0x30
>> [ 28.345010] Code: 24 08 49 c1 e9 09 49 83 f1 01 41 83 e1 01 e8 73
>> e4 ff ff 65 48 8b 04 25 c0 d4 00 00 48 89 df c7 80 fc 0c 00 00 00 00
>> 00 00 57 9d <0f> 1f 44 00 00 48 83 c4 30 5b 5d 41 5c 41 5d 41 5e 41 5f
>> c3 65
>>
>> Since request_resource() will unconditionally return a conflict for invalid
>> regions, there will be no way to break out of the loop when enabling 64bit BAR.
>> Add checks and exit the loop in these cases without attempting to enable
>> BAR.
>>
>> Signed-off-by: Bandan Das <bsd@redhat.com>
>> ---
>> arch/x86/pci/fixup.c | 7 ++++++-
>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
>> index 1e996df..8933a1b 100644
>> --- a/arch/x86/pci/fixup.c
>> +++ b/arch/x86/pci/fixup.c
>> @@ -696,8 +696,13 @@ static void pci_amd_enable_64bit_bar(struct pci_dev *dev)
>> res->end = 0xfd00000000ull - 1;
>> /* Just grab the free area behind system memory for this */
>> - while ((conflict = request_resource_conflict(&iomem_resource, res)))
>> + while ((conflict = request_resource_conflict(&iomem_resource, res))) {
>> + if ((res->start > res->end) ||
>> + (res->start < iomem_resource.start) ||
>> + (res->end > iomem_resource.end))
>> + break;
>> res->start = conflict->end + 1;
>> + }
>> dev_info(&dev->dev, "adding root bus resource %pR\n", res);
>>

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